US senators on Thursday urged greater environmental safeguards for dams on the Mekong River, calling on Washington to use its influence through global lenders to encourage a sustainable approach.

A bill introduced in the Senate applauds the delay in Laos of construction of the $3.8 billion Xayaburi project and called for further delay in Mekong River dams until assurances of adequate planning and regional cooperation.

Senator Jim Webb, a member of President Barack Obama's Democratic Party who heads a subcommittee on East Asia, called the postponement of the Xayaburi hydropower project "a positive step forward."

"I hope that all countries will abide by their commitments to complete a robust assessment of this dam before moving forward on any construction. Absent such a collaborative approach, the ecological and economic stability of Southeast Asia is at risk," Webb said in a statement.

The bill sponsored by Webb along with leading Republicans calls on the United States to use its "voice and vote" in international institutions to ensure strict environmental safeguards for Mekong River projects.

It also calls on the United States to "assist in identifying sustainable economic, water and energy alternatives to mainstream hydropower dams on the Mekong River."

More than 60 million people in the lower Mekong basin depend on the river system for food, transport and economic activity. The Xayaburi dam would have been the first of 11 such projects.

Cambodia, Thailand and Vietnam urged Laos to put off the dam, which environmentalists said would trap vital nutrients, increase algae growth and prevent dozens of species of migratory fish -- including the giant catfish -- swimming upstream to spawning grounds.

Secretary of State Hillary Clinton in 2009 launched a Lower Mekong initiative as part of a drive to re-engage Southeast Asia, with a focus on education, adapting to climate change and fighting diseases including HIV/AIDS.